940 
Thus we see in N°. 15 (fig. 1) in which the embryo has a length 
of 9 e.m. and the brain a weight of 2 grams, that on the lateral 
&. 
ze $, 6. 
6 
dee AN 2 
a 
mig ac 
3. 
surface, therefore not on its lateral edge, a small curvation is visible 
-b. It is,found above the place where, on the edge, the frontal and 
temporal part come together. This curvation is small, but plainly 
visible. If one examines the surroundings of this small line, then 
another thin line is seen, passing from the first mentioned one towards 
tbe lateral edge. It forms as it were a junction between the line 6 
and that edge. 
The curvation: 6 has developed (fig. 2) in N°. 14 (length 11 e.m., 
brain weight 3 granis) into a distinct furrow. In this embryo too, 
the junction between ¢/ and the lateral edge is not more than the 
lengthening of a furrow in the form ofa thin line a. One sees however 
on the posterior part already a beginning of a bulging rim. 
As to the form of this furrow hb, this is totally different from 
what will be found later on in the other sulei, because the rims 
are not placed opposite each other, but the anterior is flattened. 
Fig. 3 shows us this furrow transversally sectioned. In it we see 
that the posterior wall goes straight downward to the bottom of 
the furrow, but that it passes on the anterior part along a sloping 
surface to the frontal part. 
In N°. 18a (length 13.5 em., brainweight 9 grams) which is 
nearly of the same size as 13%, the direction of the suleus has 
totally altered. Where it possessed in fig. 2 a direction somewhat 
from inferior-posterior to superior-anterior, the direction in this 
embryo (fig. 4) has totally changed and runs from inferior-anterior 
to superior-posterior. The posterior wall of the future fissura Sylvii 
is now totally formed and protrudes over the anterior part. This 
border is remarkable, because it has become deeper at the lower 
portion therefore near a. Moreover in this embryo too, there has 
been formed a part of the anterior wall of the fissura Sylvii c, 
whereas the lower part d is formed by the frontal lobe. The total 
